The present disclosure relates to a vehicle seat frame, and particularly relates to a vehicle seat frame using a thin, lightweight material.
Weight reduction has been demanded for a vehicle seat frame (hereinafter referred to as a “seat frame”) as a framework of a vehicle seat. However, even with weight reduction, the strength of the seat frame needs to be maintained and improved.
Thus, in a technique described in Japanese Patent Publication JP 5657271 B, thermal treatment by high-frequency quenching, liquid carburizing, or gas carburizing is performed for a frame member forming a seat frame molded using general steel or for the entirety of the seat frame, and in this manner, the strength of the seat frame molded using the general steel is improved.
Moreover, in a technique described in Japanese Patent Publication JP 5565785 B, thin steel has a reinforcement portion, and a high hardness portion is provided at the thin steel by thermal treatment. Further, in the technique described in Japanese Patent Publication JP 5565785 B, the shape of a force transmission path formed by the reinforcement portion and the high hardness portion is a substantially truss-like shape, and therefore, the strength of a seat frame is improved.
For further weight reduction, a high tensile strength steel plate as a thin lightweight material might be sometimes used for the frame member forming the seat frame. However, molding of the high tensile strength steel plate is more difficult than that of the general steel. In the case of using such a high tensile strength steel plate, when the thermal treatment is performed for the frame member requiring strength or the entirety of the seat frame as in the technique described in Japanese Patent Publication JP 5657271 B, there is a probability that great strain is caused due to the thermal treatment, leading to lower product accuracy. Moreover, in the case of providing the reinforcement portion at the thin steel as in the technique described in Japanese Patent Publication JP 5565785 B, a weight increases by the reinforcement portion, and therefore, there is a problem in weight reduction.